The present invention generally relates to X-Y stages and charged particle beam exposure apparatuses, and more particularly to an X-Y stage which is used in machine tools, semiconductor device producing apparatuses and the like in which there are demands to make the X-Y stage compact and to move the X-Y stage at a high speed and a high precision, and to a charged particle beam exposure apparatus having such an X-Y stage.
The X-Y stage is used in machine tools, semiconductor device producing apparatuses and the like to move a member which is to be processed and is placed on the X-Y stage. Recently, there are increased demands to make the X-Y stage compact and to move the X-Y stage at a high speed and a high precision.
FIG. 1 is a perspective view showing an example of a conventional X-Y stage. The X-Y stage shown in FIG. 1 generally includes a base 100, an X-stage 101 and a Y-stage 102. A member (not shown) which is to be processed is placed on the Y-stage 102.
The base 100 has a groove 111, a pair of retainers 112 provided within the groove 111, and an upper surface 100a provided with a pair of retainers 113. Each of the retainers 112 and 113 are provided with a plurality of rotatable cylindrical rollers or balls 114. The retainers 112 and 113 are respectively movable in a direction X.
The X-stage 101 is provided on the base 100, and in this state, the retainers 112 guide a projection 115 of the X-stage 101, and the retainers 113 guide a bottom surface of the X-stage 101. In other words, the retainers 112 accurately guide the X-stage 101 in the direction X, and the retainers 113 support the weight of the X-stage 101. The X-stage 101 is fixed on one end of a rod 116, and is moved in the direction X by an actuator (not shown) that is provided on the other end of the rod 116. The retainers 112 and 113 respectively move in the direction X together with the movement of the X-stage 101.
A pair of retainers 118 are provided within a groove 117 of the X-stage 101, and a pair of retainers 119 are provided on an upper surface 101a of the X-stage 101. Each of the retainers 118 and 119 are provided with a plurality of rotatable cylindrical rollers or balls 114. The retainers 118 and 119 are respectively movable in a direction Y.
The Y-stage 102 is provided on the X-stage 101, and in this state, the retainers 118 guide a projection 120 of the Y-stage 102 and the retainers 119 guide a bottom surface of the Y-stage 102. In other words, the retainers 118 accurately guide the Y-stage 102 in the direction Y, and the retainers 119 support the weight of the Y-stage 102. The Y-stage 102 is connected to one end of a rod 122 via a slider mechanism 121 which enables movement of the Y-stage 102 in the direction X, and the Y-stage 102 is moved in the direction Y by an actuator (not shown) that is provided on the other end of the rod 122. The retainers 118 and 119 respectively move in the direction Y together with the movement of the Y-stage 102.
The Y-stage 102 of the X-Y stage having the above described construction thus moves in the X-Y directions depending on the moving directions and the moving quantities of the rods 116 and 122.
However, when an attempt was made to make the above X-Y stage compact and to realize a high speed movement and a high precision movement, the following problems occurred.
First, in order to move the X-Y stage with a high precision, it is essential that the large number of cylindrical rollers or balls 114 used are made with a high precision and are highly uniform. But there was a problem in that it is extremely difficult to manufacture the cylindrical rollers or balls 114 with the required precision and uniformity.
Second, since the X-stage 101 and the Y-stage 102 are respectively supported by the cylindrical rollers or balls 114, the X-stage 101 and the Y-stage 102 are supported at a large number of points. As a result, there was a problem in that it is difficult to accurately move the X-stage 101 and the Y-stage 102 on a plane without play, particularly because of the nonuniform dimensions of the cylindrical rollers or balls 114 introduced due to the manufacturing error. Of course, it is conceivable to make the cylindrical rollers or balls 114 from a material that has a slight resiliency so as to absorb the play between the X-stage 101 or the Y-stage 102 and its supporting plane. In this case, the cylindrical rollers or balls 114 would be resiliently deformed by the weight of the X-stage 101 or the Y-stage 102. However, when the X-stage 101 or the Y-stage 102 rides over the cylindrical columns or balls 114 which were not subjected to the weight of the X-stage 101 or the Y-stage 102 and were thus not resiliently deformed, the so-called pitching of the X-stage 101 or the Y-stage 102 would occur. This pitching is a phenomenon in which the leading end of the X-stage 101 or the Y-stage 102 moves slightly upwards as it rides over the non-deformed cylindrical rollers or balls 114 while the trailing end of the X-stage 101 or the Y-stage 102 moves slightly downwards. For this reason, if slightly resilient cylindrical rollers or balls 114 were used, a new problem would be introduced in that the movements of the X-stage and the Y-stage 102 will be discontinuous and unstable because the cylindrical rollers or balls 114 are provided at extremely small intervals (or pitch).
Third, because the X-Y stage uses a large number of parts and has a complicated construction, there were problems in that the X-Y stage as a whole is heavy and it is difficult to move the X-Y stage at a high speed. In other words, in order to move the X-stage 101, it was necessary to apply a driving force with respect to the weight of each of the X-stage 101 and the Y-stage 102.
Fourth, each of the retainers 112, 113, 118 and 119 move by utilizing the rolling frictions of the X-stage 101 and the Y-stage 102, and move in synchronism with the corresponding one of the X-stage 101 and the Y-stage 102. For this reason, retainer stoppers (not shown) are provided at ends of the X-Y stage so that the retainers 112, 113, 118 and 119 make contact with the corresponding retainer stoppers and are stopped by the corresponding retainer stoppers. However, when the retainer makes contact with the retainer stopper as the X-stage 101 and/or the Y-stage 102 moves, an error occurred in a counted value of a counter (not shown) which detects the position of the X-Y stage due to the shock that is introduced by the contact. When the error occurred in the counted value of the counter, it was impossible to continue the continuous movement of the X-Y stage, and the process had to be stopped once. In addition, in order to reduce the possibility of the retainer making contact with the retainer stopper, it was necessary to make the entire X-Y stage large, and in this case, it was impossible to realize a compact X-Y stage.
Fifth, the X-Y stage had a 3-level structure including the base 100, the X-stage 101 and the. Y-stage 102 as shown in FIG.1. In other words, the X-stage 101 is provided on the base 100, and the Y-stage 102 is provided on the X-stage 101. For this reason, a guide mechanism and the like are provided under the Y-stage 102, and there was a problem in that it is impossible to carry out a process from under the Y-stage 102 with respect to the member which is to be processed and is placed on the Y-stage 102. In addition, it was also impossible to provide an opening at a central part of the base 100 to enable processing from under the Y-stage 102, because the guide mechanism and the like are provided at a part confronting the central part.